Inhibition Effect of Kinetic Hydrate Inhibitors on the Growth of Methane Hydrate in Gas–Liquid Phase Separation State

Liwei Cheng,Bei Liu,Zhi Li,Guangjin Chen,Limin Wang

doi:10.3390/en12234482

Liwei Cheng, Bei Liu + Show 3 more

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https://doi.org/10.3390/en12234482

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Abstract

The effect of kinetic hydrate inhibitors (KHIs) on the growth of methane hydrate in the gas–liquid phase separation state is studied at the molecular level. The simulation results show that the kinetic inhibitors, named PVP and PVP-A, show good inhibitory effects on the growth of methane hydrate under the gas–liquid phase separation state, and the initial position of the kinetic hydrate inhibitors has a major effect on the growth of methane hydrates. In addition, inhibitors at different locations exhibit different inhibition performances. When the inhibitor molecules are located at the gas–liquid phase interface, increasing the contact area between the groups of the inhibitor molecules and methane is beneficial to enhance the inhibitory performance of the inhibitors. When inhibitor molecules are located at the solid–liquid phase interface, the inhibitor molecules adsorbed on the surface of the hydrate nucleus and decreased the direct contact of hydrate nucleus with the surrounding water and methane molecules, which would delay the growth of hydrate nucleus. Moreover, the increase of hydrate surface curvature and the Gibbs–Thomson effect caused by inhibitors can also reduce the growth rate of methane hydrate.

Highlights

Natural gas, mainly composed of methane, has become an important energy source because of its high combustion heat and environmental protection
Our results show that kinetic inhibitors can significantly delay the growth of the number of methane simulation results show that kinetic inhibitors can significantly delay the growth of the number of hydrate hydrate cages, and similar effects with when the inhibitor methane cages, haveinhibitory similar inhibitory effects with when themolecule inhibitoris located at solid-liquid phase interface
The effects of kinetic hydrate inhibitors (KHIs) on the growth process of methane hydrate in gas–liquid phase separation state are studied by molecular dynamics simulation

Summary

Introduction

Mainly composed of methane, has become an important energy source because of its high combustion heat and environmental protection. The natural gas required in various cities and industrial sites is mainly transported through pipelines, and generally the pipelines are in high-pressure and low-temperature environments. The large quantity use of TIs is costly and produces environmental pollution problems. More attention is being paid to the more economical and practical low-dose hydrate inhibitors (LDHIs) [3,4], which are used in low dosage, and effectively prevent the occurrence of hydrate clogging during natural gas transportation. As one of the typical LDHIs, kinetic hydrate inhibitors (KHIs), with the advantages of low dosage and high efficiency [5,6], have attracted the attention of many researchers. KHIs can inhibit hydrate formation by effectively delaying the hydrate nucleation or inhibiting hydrate growth [7,8,9,10,11,12,13]

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Conclusion